Lung cancer is the leading cause of cancer-related deaths in the world [Greenlee et al., CA Cancer J Clin 51:15-36 (2001)]. Only one in ten patients diagnosed with this disease will survive the next five years. Although lung cancer was previously an illness that affected predominately men, the lung cancer rate for women has been increasing in the last few decades, which has been attributed to the rising ratio of female to male smokers. More women die of lung cancer than any other cancer, including breast cancer, ovarian cancer and uterine cancers combined. [American Cancer Society. Cancer Facts and Figures. 2006. Atlanta: American Cancer Society (2006)]. Despite advances in surgery, chemotherapy, and radiation therapy, survival rates have barely changed in the last decade, and long-term survival remains dramatically poor.
Lung cancers can arise in any part of the lung. Ninety to 95% of cancers of the lung are thought to arise from the epithelial, or lining cells of the larger and smaller airways (bronchi and bronchioles); for this reason lung cancers are sometimes called bronchogenic carcinomas. Cancers can also arise from the pleura (the thin layer of tissue that surrounds the lungs), called mesotheliomas, or rarely from supporting tissues within the lungs, for example, blood vessels.
It has been established that lung cancer arises as a consequence of the accumulation of multiple genetic changes involving critical genes controlling cell motility, proliferation, differentiation, and apoptosis. [Sekido at al., Biochimica et Biophysica Acta 1378:F21-F59 (1998)].
According to the American Cancer Society, there are two major types of lung cancer: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). SCLC comprises about 15% of all cancers. NSCLC, however, comprises about 85% of all lung cancers and is divided into three distinct sub-types: squamous cell carcinoma (about 25-30% of the cases), large cell carcinomas (about 10-15%), and adenocarcinomas (about 40%). The cells in these sub-types differ in size, shape, and chemical make-up. These lung cancers are inclusive of bronchogenic carcinoma, bronchial carcinoids, chondromatous hamartoma, solitary pulmonary nodules, pulmonary sarcomas, undifferentiated small cell carcinoma, undifferentiated large cell carcinoma, and bronchioloalveolar carcinomas.
Current research indicates that the factor with the greatest impact on risk of lung cancer is long-term exposure to inhaled carcinogens. The most common means of such exposure is tobacco smoke.
Treatment and prognosis depend upon the histological type of cancer and the stage (degree of spread). Possible treatment modalities include surgery, chemotherapy, and/or radiotherapy.